This invention relates to drilling apparatus and more particularly to mechanism for minimizing the chances of undesired movement of the latches of an underground core barrel inner tube assembly from their latch seated position when the drilling direction is at a hole angle that is above the horizontal prior to mechanically retracting the latch retractor tube.
In at least some prior art underground core barrel inner tube assemblies, there is undesired unlatching in certain situations despite provisions and operational training to avoid such situations. This is primarily due to the pump-in seal being mounted to the latch retracting tube. The latch spring acting between the latches may be overcome and the latches sufficiently retracted when a negative pressure occurs on the xe2x80x9cdrill sidexe2x80x9d of the seal due to removal of the water supply at the outer end of the drill string or when a positive pressure occurs on the bit side of the seal due pressurized in-ground water acting to urge the latch retractor tube toward its latch retracting position. Further, the significant mass of the spear head base, seal bypass valving and latch retractor tube can develop sufficient inertia to overcome the latch spring and retract the latches as a result of jerking of the drill string or extreme drilling vibration. With undesired unlatching and the drilling direction being sufficiently great above the horizontal, the core barrel inner tube assembly can move axially outwardly with sufficient force to damage the apparatus at the drilling surface end of the drill string and/or injure drilling personnel.
In U.S. Pat. No. 6,029,758 to Novacovicci et al there is disclosed a retractable core barrel inner tube assembly that includes a drilling apparatus head assembly having valving mechanism to substantially restrict or block fluid flow through its fluid bypass channel, together with being movable to maintain a desired fluid hear in the drill string, and thereafter, being mechanically retractable to an axially outer open position in the fluid bypass channel as the head assembly is retracted in the drill string prior to the latch body being retracted.
U.S. Pat. No. 5,339,915 to Laporte et al discloses a one way retention valve in a core barrel inner tube assembly that functions to retain drilling liquid pressure in lost circulation situations resulting from, for example, drilling into a cavity or into a broken earth formation. Further, a heavy duty spring is used to create a high liquid pressure and retain a column of liquid above the core barrel inner tube assembly.
U.S. Pat. No. 3,333,647 to Karich et al discloses a core barrel inner tube assembly having spring mechanism acting between a latch body and a latch release tube to constantly urge the latch release tube to a position permitting the latches moving to a latch seated position.
In order to make improvements in underground core barrel inner tube assemblies to minimize undesired unlatching of an underground inner tube assembly in up-hole drilling (a drilling direction above the horizontal, this invention has been made.
A drilling assembly that is movable in a drill string to the inner end portion thereof for being latchingly retained therein includes a latch body having latch retracting mechanism mounted thereon for limited axial movement relative thereto for retracting the latches of the latch assembly from a latch seated position. The latch body is of a three part construction with each latch body part defining a part of a fluid bypass channel with the intermediate part being removable from the other two parts and having a seal member thereon to form a fluid seal between the latch body and the drill string. Spring mechanism acts between the latch body and the latch mechanism to constantly urge the latch mechanism to its latch seated position. A drilling tool is attached to the latch body to extend inwardly thereof, the tool being any one of, for example, a core barrel inner tube, a plug bit, an earth sampling tube and etc.
One of the objects of this invention is to provide new and novel means in up-hole drilling apparatus that is latchingly coupleable in a drill string for rendering a safety feature to minimize the chances of accidental unlatchingly coupling from a drill string during up-hole drilling operations. Another object of this invention is to provide in a drill head assembly, a new and novel latch body assembly that may be readily converted between one primarily for underground (up-hole) use and one primarily for down-hole use.
For purposes of facilitating the description of the invention, the term xe2x80x9cinnerxe2x80x9d refers to that portion of the drill string, or of the assembly, or an element of the assembly being described when, in its position xe2x80x9cfor usexe2x80x9d in, or on, the drill string is located closer to the drill bit on the drill string (or bottom of the hole being drilled) than any other portion of the apparatus being described, except where the term clearly refers to a transverse circumferential, direction, or diameter of the drill string or other apparatus being described. The term xe2x80x9couterxe2x80x9d refers to that portion of the drill string, or of the assembly, or an element of the assembly being described when, in its position xe2x80x9cfor usexe2x80x9d in, or on, the drill string is located axially more remote from the drill bit on the drill string (or bottom of the hole being drilled) than any other portion of the apparatus being described, except where the term clearly refers to a transverse circumferential, direction, or diameter of the drill string or other apparatus being described.